The present invention relates to a data transfer control device, an electronic instrument, and a data transfer control method.
In recent years, a high-speed serial transfer interface such as low voltage differential signaling (LVDS) has attracted attention as an interface standard aiming at reducing EMI noise or the like. In such a high-speed serial transfer interface, data transfer is implemented by causing a transmitter circuit to transmit serialized data using differential signals and a receiver circuit to differentially amplify the differential signals (Japanese Patent Application Laid-open No. 2001-222249).
A portable telephone includes a first instrument section provided with buttons for inputting a telephone number or a character, a second instrument section provided with a main liquid crystal display (LCD), a sub LCD, or a camera (one or a plurality of devices), and a connection section such as a hinge which connects the first and second instrument sections. In this case, the number of interconnects which pass through the connection section can be reduced by performing data transfer between a first substrate provided in the first instrument section and a second substrate provided in the second instrument section by serial transfer using serial signal lines. Therefore, a high-speed serial interface which can implement efficient serial transfer in the connection section has been demanded.
An application processor mounted on the first substrate transfers display data to the main LCD or the sub LCD. There may be a case where the main LCD or the sub LCD transfers the status information to the application processor. In this case, the display data transferred from the application processor to the main LCD or the sub LCD accounts for most of the transfer data. Therefore, the transfer method in such an application need not be a full-duplex transfer method in which data can be received while transmitting data, but may be a half-duplex transfer method in which data can be transferred in either direction but data transmission and data reception cannot be performed at the same time. The number of interconnects passing through the first and second instrument sections can be further reduced in comparison with the full-duplex transfer method by using the half-duplex transfer method, whereby the design of the connection section or the like can be facilitated.